In southwestern area of Japan, it is necessary that temperate grass pasture is utilized with tropical grass pasture, to prolong grazing period in pasture and to reduce the seasonal fluctuation of herbage production. In this experiment, tall fescue and dallisgrass were grown respectively at two levels of nitrogen fertilization, The patterns of seasonal herbage production were shown in Fig 1. The seasonal herbage productions of combined pasture were calculated in the various area ratios of tall fescue pasture to dallisgrass pasture (Fig.2, 3). As the result, it was recognized that the combined pastures had characteristics summerized as follows: 1) In yearly yield of herbage, combined pastures lie between tall fescue pasture and dallisgrass pasture. 2) The seasonal fluctuation of herbage production is smaller in combined pasture than in each component pasture, but combined pastures have high peak in June and low peak in September. The reason for forming these peaks is that each component pasture has high herbage production in June and dallisgrass pasture, has high production in September. 3) Concerning the area ratio of two pastures the seasonal fluctuation of combined pastures appeares to be smaller when tall fescue pasture is a little lager than dallisgrass pasture. 4) The seasonal fluctuation of herbage production in combined pastures decreased in the following order: high level of nitrogen fertilization in each component pasture, low nitrogen fertilization in the one and high in the other, and low nitrogen fertilization in both pastures. Because in each pasture, the seasonal fluctuation is smaller in low nitrogen fertilization than in high nitrogen fertilization.

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Crowth behaviour of roots of Z. mays and L. multiflorum (4n) were investigated in growth chamber through a time-lapse motion picture appratus under water culture condition to confirm their dynamic growth. Plants were grown under fluorescent light of 8,000-10,000 lux at plant surface with the daylength of 12 hrs. Water temperatures were controlled at 26±2℃ for Z. mays and 20±2℃ for L. multiflorum. The results are summarized as follows ; 1. Seminal root of Z. mays grew rotating its tip which was considered to be a vector of geoperception and the endogenous rotation growth rhythm. 2. Growth direction of new roots changed from vertical to diagonal in turn from the primary to the laterals to form a domed root system. 3. Roots grew rotating their tips every 6-7 hrs., the diameter of the rotational locus being three times of the thickness of the roots. These movements were observed both in seminal roots and nodal roots, and both in primary roots and branched roots. The direction of the movement was clockwise in Z. mays and the reverse in L. multiflorum and it was not certain whether this movement has a daily rhythm or not. 4. The rotation growth of roots can be elucidated ecologically as a comprehensive adaptation to grow in narrow and stubborn media of soil particles to find the least resistant space among them.

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Mitotic activities were examined in the tips of seminal roots in Zea mays (White Dent) with the conventional paraffin method in a series of continuous 10μm sections of longitudinal and/or transversal after dying with Haematoxylin-and/or Gentian Violet solution. Results obtained through microscopical examinations are as follows: 1) Location where the cells of epidermis, cortex and stele began to elongate were asymmertrical in both sides, so were the mitotic activities in the mitotic zone suggesting that these phenomena had some relationships with the rotation growth of root tips. 2) Mitotic activities terminated at 1, 400 μm from the root tips. They could be observed in all tissues of epidermis, cortex and stele and they activated most frequently in the range of 510-600μm from the root tips. 3) Mitotic ratios were calculated with the nnumber of dividing cells to total cells in dividing the sweep range of microscope into twelve sections of 30° each to count them more accurately and the data were subtotalled in two groups of half, longitudinal cylindrical sections of 100μm in length and it was found that mitotic rations of the two sections had reversed six times until the cease of mitotic activities to the distance of 1, 400μm from the root tips. This results imply again the imbalance of mitotic activities and their periodic movement in the root tissues. 4) Original cells of 10μm could enlarge to 12 to 15 times at 7mm from the root tips that implied the great force of hormonal substances concerned. Cells were longer in epidermis than in the other tissues along the elongation zone of the root. 5) Roots curved at 1.5mm from the root tips directly by the longer elongation of cells in epidermis and cortex at the convex side than the other side and the curvature was supposed to be less affected by the imbalance of mitotic activity in the root tips. It was concluded that the mechanism of rotation growth of roots might be controlled by same endogenous factors where the three-dimensional imbalance of mitotic activity and probably their periodical movements could promote the asychronous elongation of cells in the tissues of epidermis, cortex and stele and a few millimeters of root tips were supposed to be viscous that could curve easily. 6) Mitotic activities in the seminal roots were examined three-dimensionally with Lolium multifiorum, Dactylis glomerata, Phleum pratense, Sorghum sudanense, Paspalum notatum, Medicago sativa, Trifolium incarnatum and Trifolium repens and it was found that, in all of the eight species examined, there were imbalances of the activity in the mitotic zone of the roots like Z. mays as mentioned elsewhere implying there might be some relations with the rotation growth of the roots in these species.

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In order to investigate the factors which influence on in vitro dry matter digestibility (IVDMD) of sudangrass, the present experiment was conducted with the materials of different stages of the first growth. Changes of IVDMD of leaf portion and stem portion with growth stage were determined and further, the change of leaf portion IVDMD was pursued by IVDMD of respectize leaf formed on main shoot and the change of stem portion IVDMD was pursued by IVDMD of stem constituents (head, leaf sheath, rind portion and pith portion) of main shoot. The results are summarized as follows: 1. Dry matter yield was the highest at full bloom, and estimated digestible dry matter yield based on the IVDMD data was the highest also at full bloom. 2. Average daily declines of IVDMD with advancing stage were 0.3%/day for leaf portion and 0.8%/day for stem portion. As leaf percentage was reduced from 45% at elongating stage to 16% at seed maturation, whole plant IVDMD was dropped with a rate of 0.7%/day. 3. Comparing IVDMD of leaves in different stages of growth, namely, appearing upper most, 2nd full expanding and 4th one on main shoot, respective IVDMD showed lower values with advancing stages of maturity. The rate of decline of IVDMD of a leaf in its course of expansion and aging was accelerated in later growth stage. And after flag leaf appearance, IVDMD of respective leaves were declined on account of the aging. 4. When the whole leaf portion was considered, the decline of IVDMD with growth stage was attributable to ascending of the yield portion from leaves of lower to higher insertion levels having lower IVDMD, and the aging. 5. The study on IVDMD of stem constituents of main shoot suggested that the decline, of stem portion IVDMD resulted from the growth and aging of leaf sheath, the formation of "true stem" with internodal elongation, and the hardening of stem through heading especially of rind portion which had larger partition.

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The variation of fructosanase activity in the sliced haplocorms of timothy plant (Phleum pratense L.) treated with gibberellic acid or kinetin was almost the same as that in those non-treated with any plant growth regulator, the activity increasing unti a maximum was attained after about 24hr incubation. The fructosanase activity in the sliced haplocorms treated with indole-3-acetic acid continued to increase during the incubation period tested (48hr). The development of invertase activity in the sliced haplocorms was not affected by treatment with indole-3-acetic acid in the course of experiment. Fructosan content remaining in the sliced haplocorms was inversely related to the level of fructosanase activity.

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A series of experiments was carried out to clarify the effect of shading on the growth of African millet. The plants were divided into two groups and then grown under contrasting light condition of (a) full sunlight, (b) shaded to 60% of full sunlight. 1. Effect of continuous shading: The rate of reduction of the dry weight due to continuous shading attained highest value at 20 days after commencement of shading and this being greater with root than with shoot, with leaf sheath than with leaf blade and culm. Total nitrogen %(T-N%) was increased and total available carbohydorate %(TAC%) was decreased as shading treatments were continued. The ratio of T-N% of plants under 60% shading to full sunlight was heighest at 20 days after commencement of shading and lowest in TAC%. 2. Effects of different period of shading (10-20 days) at different growth stages of plants: Dry weight of plants at cutting was recorded higher with 10 days shading than 20 days shading, but dry weight of regrowth of plants was reduced more markedly with 10 days shading than 20 days shading. 3. Effect of shading prior to cutting at different growth stages on the growth under different level of nitrogen application: The reduction of dry weight due to shading at cutting and regrowth was shown greater at early growth stage and under high level of nitrogen application. 4. Relation between shading and regrowth reported here seems to be explained by the growth stage of tillers at the time of cutting as morphological factor and T-N%, TAC% as physiological factors.

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The grassland established by ploughing and harrowing after shredding the vegetation on the Miscanthus type natural grassland. A comparative study was conducted on this grassland on the yield, the vegetation and the soil characteristics resultant from the two differing methods of utilization of grazing and cutting. The following results were obtained. 1. The amount of grass consumed by the livestock on the pasture was in weight approximately one half of the amount of grass produced by the pasture and again approximately two thirds of the grass yield on the meadow. 2. The pasture developed dung patches amounting to 20-30% of the total grazing ground and also produced localized bare land by the trampling. On the other hand, it showed less growth of stumps of orchardgrass and a lower percentage of bare land than in the meadow. 3. A comparison made on the grass yield for one year period following the termination of the grazing experiment did not indicate any significant difference in the yield of dry matter between the pasture and the meadow but did show a higher yield of crude protein in case of the pasture. 4. The soil of the pasture had higher nitrogen content than the soil of the meadow and soil layer of 0-15cm of the pasture showed compaction due to tread pressure.

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This experiment was conducted to find out suitable method of undersowing Italian ryegrass into Kazungula setaria (Setaria anceps cv. Kazungula) sward as an aftercrop of this annual warm-season grasses. Two early cultivars of Italian ryegrass (Lolium muttiflorum) i.e. Waseyutaka and Yamakei No.13 (abbreviated -1 and -13 respectively in Tables and Figures) were combined with 3 heights i.e. 0, 5 and 15cm above ground level (abb. 0-, 5- and 15- respectively) of final cutting of preceding setaria crop, which was practised immediately before the undersowing. Results are summarized as follows, 1) The height of ryegrass seedling surpassed that of setaria within one month after sowing in spite of reduced 50% light condition caused by the aftermath of the 15cm cut stubble of setaria comparing with 0cm cut plot, which was regarded as the control because no regrowth was resulted (Fig.1). 2) Undersowing environment was observed as compared with the control plot (0-1) as shown in Fig.2. Undersowing seemed to be favorable for germination process because of higher temperature and soil moisture caused by the aftermath, but no significant difference in the process was found between these plots (Table 1). 3) Extended plant height and checked development of root characterized the early growth of undersown ryegrass, but aboveground part was not significantly retarded in dry matter weight comparing with the control (Table 2). 4) Ryegrass cv. -1 was superior to cv. -13 in terms of the total yeild, though which was not significantly affected by the cutting height of preceding setaria (Fig.3). 5) Consequently, these cultivars of ryegrass are recognized to be capable of under-sowing condition of 50% reduced light for one month of duration.

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This experiment was conducted to investigate the water-stable aggregate formation of grassland soil and the effect of soil polysaccharides as a factor of this aggregate formation. Two soils having different texture and grassland history were used. The results are summarized as follows ; (1) By the investigation with vertical distribution of pasturage roots, the roots are concentrated in top horizon. In case of permanent grassland, the roots about 80 per cent of all come into existence in the region of 10cm bellow from the ground surface. (2) According to the analysis of water-stable aggregates, with the growth of pasturage roots, effective soil aggregates (>1mm) were developed. (3) Soil polysaccharides are determined for the hydrolyzate which are obtained from each aggregate-size. Amount of extracted soil polysaccharides show a tendency to increase in proportion to the aggregate-size. However, the relation can not be observed between aggregate-size and uronic acid content of soil hydrolyzates. (4) Composition of soil polysaccharides are examined with thin-layer chromatography method. The kind of constituent sugars of polysaccharides in the newly established grassland soil is more diverse than permanent grassland soil. (5) It is considered that soil origin exerts a greater influence on composition of soil polysaccharides than the cropping history does.

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First-cut good quality Italian ryegrass hay containing crude protein of 15.6% on dry matter basis was offered to four Japanese native castrated male goats at four levels of dry matter intake (0.7, 1.4, 2.1 or 2.8% of body weight) in a 4×4 Latin square design and the effect of level of intake on digestibility and nitrogen balance was studied. In the digestion trial, goats fed rations at 0.7 and 1.4% levels lost their weights, but those fed rations at 2.1 and 2.8% levels gained their weights. The digestibility and, DCP and TDN contents of the hay decreased as the level of intake increased, and especially, they were significantly lower for the group fed at 2.8% level than for the other three groups. The significant difference in nitrogen balance was observed between the group fed at 0.7% level which showed a negative balance and the other three groups which showed a positive balance. A linear regression equation and a coefficient of corelation between the dry matter digestibility and the percent of dry matter intake to body weight were obtained as follows ; y=76.44-2.45x r=-0.815 where y=dry matter digestibility and x=percent of dry matter intake to body weight. From these results it was suggested that the digestibility of even a good quality hay containing crude protein of about 16% decreased as the level of intake increased, therefore, the level of intake must be taken into consideration when the feeding value of roughages was estimated by feeding trials.

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In the early summer of 1971, an extensive outbreak of the oriental armyworm, Mythimna separata Walker, occurred on grasslands of Tohoku district, northern Japan. In a previous paper it was suggested that the outbreak might be caused by an immigration of the moth swarms brought by a southwesterly air-current which came from continental China to northern Japan on 25th May. However, the critical period of moth immigration is estimated to be in early June, if we take the thermal constant and the threshold temperature of the army-worm growth obtained by Okuyama and Tomioka as the substitute for those by Lin and Cheng, which were formerly employed for the estimation. During the early half of June, a strong southwesterly wind established over Tohoku district on the night of 4th June. Synoptic weather charts indicated that this wind followed a depression which rapidly moved towards northern Japan from Honan district of eastern China, where the moths emerge during late May and early June. On the other hand, the depression which caused the south-westerly wind of 25th May originated in the more south, where the moth activity was terminated ahead of this period. The results of moth trapping in two localities of Tohoku district supported the supposition that the moth swarms invaded the district on 4th June. Some comments upon the topographic effect on the migratory routes in mountainous areas of the district were given herewith.

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